Determining ecosystem properties and short-term dynamical simulations in Eisenia cokeri kelp forest (north-center of Peru): Implications for conservation and monitoring

Abstract

A mass-balanced and dynamical multispecies trophic model was constructed for the kelp forest ecosystem dominated by Eisenia cokeri in the central-northern Peruvian coast. Information of biomass, productivity, food spectrum, consumption, catches, and dynamics of the commercial and non-commercial local populations was needed and examined using Ecopath with Ecosim (EwE) software. The brown macroalgae E. cokeri accounted for ∼60% of total system biomass, ∼30% of total system throughput (TST), and ∼26% of ascendency (A), indicating its relevance in the aggregation and transference of energy/matter in the network, as well as in the development and growth status of this coastal ecological system. Based on the values of TST, A, A/C and Ov/C ratios, and path redundancy, this kelp forest would be more developed but less resistant to disturbances than other kelp forests along the SE Pacific and Antarctic coast. Likewise, Luidia magellanica, Heliaster helianthus and Labrisomus phillipi were the components that accounted for the complexity (lowest % of AMI) of the benthic-pelagic network system. The outcomes of mixed trophic impacts (MTI) indicate that the asteroids L. magellanica, H. helianthus, and other sea stars (OSS) propagate the highest magnitudes of direct and indirect effects on the other model compartments. Meanwhile, the dynamical responses using Ecosim short-term simulations (increasing 10%, 30%, and 50% the total mortality by fishing), the brown macroalgae E. cokeri, small epifauna (SE), and Tegula spp. exhibited the highest impacts on the remaining compartments in the model-system. The system recovery time (SRT) (as a measure of system resilience) indicated that E. cokeri, H. helianthus, and Tegula spp. would take the longest time to return (after disturbance) to their initial condition. The macroscopic properties estimated in the present work could be considered as baseline ecosystem conditions before performing an intensive exploitation on E. cokeri.